This invention relates to an improved pulsation dampener or surge absorber and an improved diaphragm for use in same.
The art of dampening the pressure surges or puslations in a stream of incompressible fluid has risen to a high level of skill. Examples of the technology of this art are reflected in the following patents that are assigned to the assignee of the present invention:
______________________________________ U.S. Pat. No. PATENTEE ISSUE DATE ______________________________________ 2,757,689 Knox Aug. 7, 1956 2,804,884 Knox Sept. 3, 1957 3,169,551 Lewis Feb. 16, 1965 3,674,053 Murman July 4, 1972 3,880,193 Lewis Apr. 29, 1975 ______________________________________
While the embodiment disclosed in Knox U.S. Pat. No. 2,757,689 has been extremely successful, it did possess certain disadvantages. First, the inner wall of the pressure vessel was exposed to the fluid being pressure dampened which could be damaged if the dampening fluid was corrosive. Secondly, the mounting means for the pressure vessel was integral with the inlet for the fluid being pressure dampened. Thus, erosion and/or corrosion of the inlet nozzle by the pressure dampened fluid will require replacement of both the inlet nozzle and the securing means. As the latter item is relatively expensive to machine or form, the cost of repair of the pulsation dampener is also increased. U.S. Pat. Nos. 2,804,884 and 3,169,551 are similar in construction to the previously discussed Knox patent and possess the same disadvantages.
In Murman U.S. Pat. No. 3,674,053, the diaphragm is inverted for protecting the metal pressure vessel shell from the fluid being pressure dampened. The inlet nozzle is formed with the threads for connecting with a conduit containing the pulsating fluid. In addition, no means are provided to control wrinkling of the diaphragm when the reference fluid pressure greatly exceeds the fluid pressure of the fluid being pressure dampened.
Bladders or diaphragms are known which fold back or overlap themselves on one side under certain pressure conditions. One such example is disclosed in Peters U.S. Pat. No. 3,162,213. To control folding of the bladder or diaphragm, external stiffeners, such as disclosed in Overbeke U.S. Pat. No. 2,380,866, have been used.
In U.S. Pat. Nos. 2,378,467 and 2,397,248, both to DeKiss, there is disclosed accumulator bladders that overlap and which have integral molded annular ribs or beads which control the radius of curvature of the bladder at the fold. Such a rib is required because at low temperatures the diaphragm may become brittle and crack when folded flat upon itself without a radius of curvature being provided. In both DeKiss disclosures, the bladder is not arranged for isolating the pulsating fluid from the pressure vessel. The DeKiss patents also make a distinction between a bladder and a diaphragm type accumulator. In the present disclosure, however, it is to be understood that diaphragm and bladder are to be considered to be used interchangeably as the flexible separation element, unless expressly stated otherwise.
The Lippincott U.S. Pat. No. 2,397,796 also discloses a diaphragm having a rib to control the reverse bending to prevent cracking, but like the DeKiss patents, the fluid to be dampened is exposed to the pressure vessel.